CRESSIDA Bonas has been officially recognised as Prince Harry's partner by being asked to co-host a formal dinner honouring war heroes at St James's Palace.

Cressida was seen staring adoringly at Harry during Twickenham earlier this month [REX]

The 25 year-old, who has been seeing Harry, 29, for two years, has been invited to help him host a private dinner party for friends he made during a 208 mile trek to the South Pole last year.

Harry is a patron of the Walking With The Wounded charity, which organised the trek, and which helps injured veterans dealing with life-changing injuries.

The dinner will be held on March 27, and it is expected that Miss Bonas will accept the invitation.

While her role will not involve formally greeting guests, as the Duchess of Cambridge does when hosting events with Prince William, a source said she will effectively share hosting duties with Prince Harry.

The pair are believed to have been seeing each other for two years [GETTY]

The source added: "Harry and his mates went through thick and thin together, so the dinner party will be a really relaxed and jovial affair.

"But there is no doubt that it will be a Royal banquet, albeit a private one."

Another source said that, while not technically an official Royal event, the dinner marked an official engagement for the couple.

The State Apartments at St James's Palace are used for State visits and hosting receptions for charities, and can also be used by courtiers for private events such as weddings.

The invitation follows a public display of affection between Harry and Cressida as they attended the We Day youth event at Wembley arena.

The usually private pair also attended the rugby at Twickenham as a couple.